Showing papers on "Heterodera avenae published in 2016"

Association analysis of resistance to cereal cyst nematodes (Heterodera avenae) and root lesion nematodes (Pratylenchus neglectus and P. thornei) in CIMMYT advanced spring wheat lines for semi-arid conditions

Abstract: To identify loci linked to nematode resistance genes, a total of 126 of CIMMYT advanced spring wheat lines adapted to semi-arid conditions were screened for resistance to Heterodera avenae, Pratylenchus neglectus, and P. thornei, of which 107 lines were genotyped with 1,310 DArT. Association of DArT markers with nematode response was analyzed using the general linear model. Results showed that 11 markers were associated with resistance to H. avenae (pathotype Ha21), 25 markers with resistance to P. neglectus, and 9 significant markers were identified to be linked with resistance to P. thornei. In this work we confirmed that chromosome 4A (~90-105 cM) can be a source of resistance to P. thornei as has been recently reported. Other significant markers were also identified on chromosomal regions where no resistant genes have been reported for both nematodes species. These novel QTL were mapped to chromosomes 5A, 6A, and 7A for H. avenae; on chromosomes 1A, 1B, 3A, 3B, 6B, 7AS, and 7D for P. neglectus; and on chromosomes 1D, 2A, and 5B for P. thornei and represent potentially new loci linked to resistance that may be useful for selecting parents and deploying resistance into elite germplasm adapted to regions where nematodes are causing problem.

Molecular Characterization of A Novel Effector Expansin-like Protein from Heterodera avenae that Induces Cell Death in Nicotiana benthamiana.

Abstract: Cereal cyst nematodes are sedentary biotrophic endoparasites that maintain a complex interaction with their host plants. Nematode effector proteins are synthesized in the oesophageal glands and are secreted into plant tissues through the stylet. To understand the function of nematode effectors in parasitic plants, we cloned predicted effectors genes from Heterodera avenae and transiently expressed them in Nicotiana benthamiana. Infiltration assays showed that HaEXPB2, a predicted expansin-like protein, caused cell death in N. benthamiana. In situ hybridization showed that HaEXPB2 transcripts were localised within the subventral gland cells of the pre-parasitic second-stage nematode. HaEXPB2 had the highest expression levels in parasitic second-stage juveniles. Subcellular localization assays revealed that HaEXPB2 could be localized in the plant cell wall after H. avenae infection.This The cell wall localization was likely affected by its N-terminal and C-terminal regions. In addition, we found that HaEXPB2 bound to cellulose and its carbohydrate-binding domain was required for this binding. The infectivity of H. avenae was significantly reduced when HaEXPB2 was knocked down by RNA interference in vitro. This study indicates that HaEXPB2 may play an important role in the parasitism of H. avenae through targeting the host cell wall.

Characterization of Three Novel Fatty Acid- and Retinoid-Binding Protein Genes (Ha-far-1, Ha-far-2 and Hf-far-1) from the Cereal Cyst Nematodes Heterodera avenae and H. filipjevi.

Abstract: Heterodera avenae and H. filipjevi are major parasites of wheat, reducing production worldwide. Both are sedentary endoparasitic nematodes, and their development and parasitism depend strongly on nutrients obtained from hosts. Secreted fatty acid- and retinol-binding (FAR) proteins are nematode-specific lipid carrier proteins used for nutrient acquisition as well as suppression of plant defenses. In this study, we obtained three novel FAR genes Ha-far-1 (KU877266), Ha-far-2 (KU877267), Hf-far-1 (KU877268). Ha-far-1 and Ha-far-2 were cloned from H. avenae, encoding proteins of 191 and 280 amino acids with molecular masses about 17 and 30 kDa, respectively and sequence identity of 28%. Protein Blast in NCBI revealed that Ha-FAR-1 sequence is 78% similar to the Gp-FAR-1 protein from Globodera pallida, while Ha-FAR-2 is 30% similar to Rs-FAR-1 from Radopholus similis. Only one FAR protein Hf-FAR-1was identified in H. filipjevi; it had 96% sequence identity to Ha-FAR-1. The three proteins are alpha-helix-rich and contain the conserved domain of Gp-FAR-1, but Ha-FAR-2 had a remarkable peptide at the C-terminus which was random-coil-rich. Both Ha-FAR-1 and Hf-FAR-1 had casein kinase II phosphorylation sites, while Ha-FAR-2 had predicted N-glycosylation sites. Phylogenetic analysis showed that the three proteins clustered together, though Ha-FAR-1 and Hf-FAR-1 adjoined each other in a plant-parasitic nematode branch, but Ha-FAR-2 was distinct from the other proteins in the group. Fluorescence-based ligand binding analysis showed the three FAR proteins bound to a fluorescent fatty acid derivative and retinol and with dissociation constants similar to FARs from other species, though Ha-FAR-2 binding ability was weaker than that of the two others. In situ hybridization detected mRNAs of Ha-far-1 and Ha-far-2 in the hypodermis. The qRT-PCR results showed that the Ha-far-1and Ha-far-2 were expressed in all developmental stages; Ha-far-1 expressed 70 times more than Ha-far-2 in all stages. The highest expression level of Ha-far-1 was observed in fourth-stage juvenile (J4), whereas the highest expression level of Ha-far-2 occurred in second-stage juvenile (J2). In conclusion, we have identified two novel far genes from H. avenae and one from H. filipjevi and have provided further indication that nematode far genes are present in a variety of nematode species, where the FAR proteins share similar basic structure, expression pattern and biochemical activities.

Spring Barley Resistance and Tolerance to the Cereal Cyst Nematode Heterodera avenae.

Abstract: Heterodera avenae is a cereal cyst nematode that reduces wheat yields in the Pacific Northwest of the United States. Barley is also susceptible but there were no previous reports of resistance or tolerance to H. avenae in the United States. Spring barley cultivars were assayed in H. avenae-infested fields over 2 years. Cultivars were planted in plots treated or not treated with aldicarb. Forty-five cultivars were evaluated for the market classes of two- and six-row feed barley cultivars and two- and six-row malt barley cultivars. One two-row feed barley ('Lenetah') was ranked as resistant and four were tolerant or very tolerant. In total, 1 two-row malt barley ('Odyssey') was very resistant and 10 were tolerant or very tolerant. Two six-row feed and two six-row malt barley cultivars were tolerant or very tolerant but none were resistant. Seven feed barley cultivars were ranked as having a balance of at least moderate resistance plus moderate tolerance: 'Champion', Lenetah, 'Xena', 'Idagold II', 'Transit', 'Millennium', and 'Goldeneye'. This is the first report of resistance and tolerance of barley in H. avenae-infested fields in the Pacific Northwest. Barley productivity can be improved by planting resistant plus tolerant cultivars or by using highly resistant and highly tolerant cultivars as parents in barley improvement programs.

Root-lesion and cyst nematodes in cereals fields in Morocco : Species identification, population diversity and crop resistance

Abstract: Cereal cyst nematodes (CCN, Heterodera spp.) and root-lesion nematodes (RLN, Pratylenchus spp.) are important plant-parasitic nematodes of wheat and exist in most of the cereal growing regions of the world. As there was limited information on the distribution of CCN and RLN species in wheat fields in Morocco, a survey was organized in 2011. A total of 75 soil and root samples were collected from fields in Gharb, Saiss, Zaers and Chaouia before the wheat and barley harvest (May to June). Cysts were extracted from soil by flotation and decanting through 200-μm sieves. Vermiform stages were extracted from roots and soil with an automated zonal centrifuge. They were identified up to species level using morphological and molecular methods. The survey revealed that 69% of the samples were infested with four species of Pratylenchus, viz. P. thornei, P. penetrans, P. pseudocoffeae and P. pinguicaudatus. The most prevalent species was P. penetrans, present in the four regions. Cereal cyst nematodes were found in 16% of the soil samples and were represented by two species, viz. H. avenae and H. latipons. Heterodera avenae was the most prevalent, occurring in 13% of the fields and associated with wheat in the 3 regions where it was found. Heterodera latipons was detected only in one sample, originating from Ain Jmaa (Saiss). The morphological and molecular characteristics of 11 populations of CCN collected from different wheat growing regions of Morocco were studied. Morphometrics of cysts and second-stage juveniles (J2) were generally within the expected ranges for H. avenae; only the isolate from Ain Jmaa showed morphometrics conforming those of H. latipons. When using species-specific primers for H. avenae and H. latipons, the specific bands of 109 bp and 204 bp, respectively, confirmed the morphological identification. In addition, the internal transcribed spacer (ITS) regions were sequenced to study the diversity of the 11 populations. These sequences were compared with those of Heterodera species available in the GenBank database (www.ncbi.nlm.nih.gov) and confirmed again the identity of the species. Ten sequences of the ITS-rDNA were similar (99-100%) to the sequences of H. avenae published in GenBank and three sequences, corresponding with one population, were similar (97-99%) to H. latipons. During the survey of the wheat-growing area of Morocco, 17 populations of RLN were collected. They were identified on the basis of their morphological and morphometric characters, and by molecular methods. Microscopic observations of females and males demonstrated the occurrence of P. penetrans in 13 of the 17 samples; P. thornei and P. pseudocoffeae were detected in four samples from Zaers and a single sample from Settat, respectively. A duplex PCR primer set was used to confirm the presence of P. penetrans while the species-specific forward primer PTHO and the common reverse primer D3B were used for P. thornei. For the remaining populations, the D2-D3 expansion segments of the 28S rRNA gene were amplified and the obtained sequences were compared with those of Pratylenchus species in the GenBank database. This comparison confirmed the morphological identifications and revealed a population of P. pinguicaudatus. The study of the phylogenetic relationship of the Moroccan Pratylenchus populations showed a high similarity (99- 100%) between all P. penetrans populations. The population dynamics of six Pratylenchus populations from Morocco were evaluated on carrot-disk cultures at 4, 8 and 12 weeks after inoculation, and at 10, 15, 20 and 25°C. The optimum temperature for reproduction of all populations was 20°C. After 8 weeks at this temperature, nematode numbers increased up to 458-fold, 310-fold and 252-fold for the four populations of P. penetrans, the P. thornei and the P. pseudocoffeae populations, respectively. A real-time quantitative PCR assay was developed for the accurate detection and quantification of another root-lesion nematode, P. thornei. A qPCR primer set, including two primers and a probe, was designed based on the sequence of the β-1,4- endoglucanase gene. The assay was optimised by using the primers with SYBR green I dye and setting the qPCR program to different annealing temperatures ranging from 62 to 69°C. Based on the Ct values, the program with an annealing temperature of 69°C was retained. The specificity of the qPCR assay including the probe was confirmed by the lack of amplification of DNA from 47 populations belonging to 15 other Pratylenchus species, while DNA from nine isolates from P. thornei was amplified. The assay was very sensitive as it was able to detect a single individual of P. thornei, even when mixed with up to 80 individuals of P. penetrans. DNA was extracted from exactly 80 P. thornei individuals. A dilution series from this DNA resulted in a standard curve showing a highly significant linearity between the Ct values and the dilution rates (R2=0.98; slope=−3.38; E=97.6%). The qPCR assay proved to be specific and sensitive, thus providing a fast and accurate tool for detection and quantification of P. thornei during research, as well as for diagnostic labs. Breeding for resistant varieties is one of the most effective methods to control nematodes. A collection of 14 spring wheat and of 11 winter wheat lines, developed at CIMMYT, for resistance to both nematode species. Individual plants were grown in sand in small tubes (15× 20× 120 mm) placed in a random design with ten replicates in the greenhouse. The resistance level was evaluated based on the numbers of nematodes extracted from both roots and soil of each line. Trials were terminated 9 weeks after nematode inoculation. The numbers of P. penetrans and P. thornei were determined using a microscope. Three lines (L9, L12 and L13) were found resistant to P. thornei and one of these (L9) was also resistant to P. penetrans. To investigate the stability of this resistance, J2 of Heterodera avenae were simultaneously inoculated. The reproduction of both lesion nematodes P. penetrans and P. thornei, was assessed both by counting and by using the developed qPCR assays. Our results showed that the wheat lines L9 and L9, L12, L13 remained resistant to P. penetrans and P. thornei, respectively. The outcome of this study is valuable to wheat breeding programmes in Morocco and the world. However, the resistant lines should be validated under natural field conditions. These findings are important to understand the background of the source(s) of resistance responsible for inhibition of nematode reproductions in promising wheat lines.

Biocontrol of cereal cyst nematode by Streptomyces anulatus isolate S07

Abstract: An actinomyce (S07) isolated from a cyst of Heterodera filipjevi was characterised as Streptomyces anulatus by morphological, physiological and biochemical criteria and 16S rRNA analysis. The biocontrol potential of S07 was evaluated against both Heterodera avenae and H. filipjevi. After an initial assay of S07 culture filtrates on egg hatch in vitro and juvenile survival, the effect on these cereal cyst nematodes (CCN) was evaluated in the greenhouse using naturally infested soil and in the field over two consecutive years. The results showed that S07 significantly reduced the population densities of CCN females in wheat, concurrently increasing grain yield. It is concluded that S07 offers potential as a commercial biocontrol agent.

Characterization of Resistance to the Cereal Cyst Nematode in the Soft White Winter Wheat ‘Madsen’

Abstract: The cereal cyst nematode (CCN) has a significant negative impact on production of wheat in China. The presence of pathotypes of both Heterodera avenae and H. filipjevi makes it necessary to identify genetic resources with a wide spectrum of resistance. Results of this study confirmed that the soft white winter wheat 'Madsen' was resistant to many different populations of both H. filipjevi and H. avenae in both naturally infested fields and artificial inoculation tests in China. Fewer juvenile nematodes penetrated roots of Madsen than susceptible 'Wenmai 19' in the early stages of the interaction between the nematodes and plant. Testing wheat cultivars in the pedigree of Madsen demonstrated that the CCN resistance of Madsen was inherited from 'VPM1' via the line 'VPM1/Moisson 951'. Presence of a 2NS chromosome segment from Aegilops ventricosa was detected in Madsen using a Vrga1D-specific marker. However, it appears that gene Pm4b for resistance to powdery mildew (caused by Blumeria graminis f. sp. tritici) was not transferred from VPM1 into Madsen because these cultivars had different reaction patterns against 20 B. graminis f. sp. tritici isolates from China. Madsen serves as an effective source of host resistance from damage caused by CCN.

Molecular Cloning and Characterization of Two Genes Encoding Tryptophan Decarboxylase from Aegilops variabilis with Resistance to the Cereal Cyst Nematode (Heterodera avenae) and Root-Knot Nematode (Meloidogyne naasi)

Abstract: Tryptophan decarboxylase (TDC), which catalyzes the conversion of Trp to tryptamine, provides a common backbone for many secondary metabolites, and is important in defending plants from abiotic stress such as pathogen infection and insect attack. In this study, we cloned two TDC genes, AeVTDC1 and AeVTDC2, from Ae. variabilis accession No. 1 with resistance to cereal cyst nematode (CCN) and root-knot nematode (RKN). AeVTDC1 and AeVTDC2 encode polypeptides of 510 and 518 amino acids, respectively, and both have a pyridoxal phosphate attachment site and specific catalytic residues. Comparative analyses of gene structure and amino acid motifs revealed that TDCs are highly conserved crossing the analyzed species in monocots and dicots. Phylogenetic analysis indicated that AeVTDCs were closer to TDCs of wheat, Ae. tauschii, Triticum urartu, Brachypodium distachyon, and Hordeum vulgare. Their functions and temporal and spatial expression patterns were investigated. Moreover, AeVTDC1 and AeVTDC2 exhibited different expression responses to the phytohormones abscisic acid, salicylic acid, and methyl jasmonate, suggesting that they may function differently in response to biotic and abiotic stresses. The inhibition of TDC activity with S-αFMT resulted in susceptibility of Ae. variabilis to CCN and RKN, suggesting that TDCs may play important roles in resistance to nematodes.

Detection of Dual Heterodera avenae Resistance plus Tolerance Traits in Spring Wheat

Abstract: The cereal cyst nematode Heterodera avenae reduces wheat yield in the Pacific Northwest. Resistance and tolerance traits among spring wheat cultivars were poorly defined. Screening trials were conducted with 39 cultivars over a 2-year period in irrigated commercial fields that were infested by H. avenae. Comparisons were made between drill strips treated or untreated with aldicarb at the time of planting. Root sampling at the time of plant anthesis indicated that cultivars differed greatly in susceptibility to H. avenae, with numbers of newly produced white H. avenae females ranging from <5 to 70 per plant. Aldicarb reduced mean numbers of white females as much as 99% on the most susceptible cultivar ('Glee') and increased mean grain yield as much as 77% for the least tolerant cultivar ('Cataldo'). Density of H. avenae eggs in untreated soil following harvest was significantly higher than the density in aldicarb-treated plots. Agronomically acceptable traits of resistance plus tolerance were identified in one cultivar of hard red spring wheat ('WB-Rockland') and two cultivars of hard white spring wheat ('Klasic' and 'LCS Star') but in none of the soft white spring wheat cultivars. This is the first report of spring wheat cultivars expressing the dual traits of resistance plus tolerance to H. avenae.

Testing and modelling the potential of three diploid plants in Poaceae as a new pathosystem to investigate the interactions between cereal hosts and cereal cyst nematode (Heterodera avenae)

Abstract: Cereal cyst nematode (CCN), Heterodera avenae, is one of the most important pathogens of wheat worldwide, and causes significant yield losses. Research on CCN–wheat interactions is hampered by the lack of an effective model pathosystem. This study investigated the potential of the model cereal Brachypodium distachyon (Bd21-3) and diploid wheat 2A (G1812) and 2D (AL8/78) as model hosts for CCN. Nematode infection analysis showed that although some CCN penetrated Bd21-3 roots, these nematodes failed to develop to the later developmental stages or form cysts, indicating B. distachyon is not a host for CCN. A strong burst of reactive oxygen species (ROS) within Bd21-3 roots infected with CCN was induced 3 days after infection and the expression of seven ROS-producing genes was significantly increased. In contrast, CCN completed its life cycle in both diploid wheat 2A and 2D, and formed normal syncytia in these hosts. Although CCN developmental processes within both diploid wheat 2A and 2D were very similar to those in the susceptible control, the number of cysts formed on diploid wheat 2D was less than those formed on diploid wheat 2A and the susceptible control, indicating that diploid wheat 2A was a more suitable host for CCN than 2D. This is the first report of a potential new pathosystem for CCN–host interactions using diploid wheat.

Morphological and molecular identification of potato and cereal cyst nematode isolates from Algeria and their phylogenetic relationships with other populations from distant theirgeographical areas

Abstract: A nematode survey conducted in 2013 in Algeria, revealed that potato cyst nematodes (PCN) and cereal cyst nematodes (CCN) are widely distributed in several potato and cereal growing regions of the country. Sixteen PCN populations from five localities and five CCN populations from four of these localities were collected and characterized at the morphological and molecular levels. The PCN populations were identified as Globodera rostochiensis and G. pallida occurring separately or in mixed populations. Two species of CCN were detected. Heterodera avenae was found in four localities, whereas H. hordecalis only in one locality in association with H. avenae. The morphological and morphometric identification of PCN and CCN was confirmed by diagnostic ITS-RFLP profiles and sequencing. Phylogenetic analysis of the ITS, D2-D3 expansion domains of the 28S rRNA gene and 18S rRNA gene was made for PCN and CCN populations. Globodera pallida and G. rostochiensis from Algeria show great similarity with European and South American populations. Because of the high divergence among Algerian populations of G. pallida and G. rostochiensis it can be assumed that they were multi-introduced in Algeria. The most divergent population of G. pallida, that formed a well-separated group with some populations from Chile and Peru, suggests a later or independent introduction of this population into Algeria. Heterodera avenae and H. hordecalis formed a well-supported cluster with the corresponding populations.

GC-MS Analysis of Nematicidal Essential Oil of Mentha canadensis Aerial Parts against Heterodera avenae and Meloidogyne incognita

Abstract: The essential oil of Mentha canadensis aerial parts was obtained by hydrodistillation and analyzed by gas chromatography (GC) and gas chromaotography-mas spectrometry (GC-MS). A total of 36 components of the essential oil were identified. The major constituents in the essential oil of M. canadensis were menthol (28.8 %), α-pinene (16.4 %), menthone (12.7 %), α-terpineol (6.3 %) and limonene (5.5 %). Four active constituents (limonene, menthol, α-pinene and α-terpinol) were isolated from the essential oil of M. canadensis based on bioactivity-directed fractionation. The essential oil of M. canadensis aerial parts exhibited nematicidal activity against cereal cyst nematodes (Heterodera avenae) and root-knot nematodes (Meloidogyne incognita) with LC values of 385.7 μg/ml and 139.0 μg/ml, respectively. The isolated constituents, menthol and α-terpinol possessed nematicidal activity against H. avenae and M. incognita with LC50 values of 242.5 μg/ml, 190.3 μg/ml and 147.4 μg/ml, 115.2 μg/ml, respectivel...

The cell wall microstructures of syncytia induced by cyst nematodes

Abstract: Plant parasitic cyst nematodes induce the formation of specialised feeding structures, termed syncytia, from which they feed within the host roots. The multinucleate syncytium initiates from a single host root cell and expands by the local cell wall dissolution of neighbouring cells. In this study, a set of monoclonal antibodies were applied to reveal the microstructures of syncytial cell walls induced by four economically important cyst nematode species, Globodera pallida, Heterodera glycines, Heterodera avenae and Heterodera filipjevi, in their respective potato, soybean and wheat host roots. In situ fluorescence analysis revealed that cell walls of syncytia induced by G. pallida and H. glycines share high structural similarity. Both consisted of abundant xyloglucans, methyl-esterified homogalacturonan and pectic arabinans. In contrast, the walls of syncytia induced in wheat roots by H. avenae and H. filipjevi contain much less xyloglucan but are rich in feruloylated and substituted heteroxylans and arabinans, with variable levels of mixed-linkage glucans and galactans. Further investigations were implemented using a range of cell wall related Arabidopsis xyloglucan and pectic arabinan mutants. In situ analysis was applied on those H. schachtii induced syncytia. The results indicated the strong adaptions during the induction and formation of the syncytia while the cell wall composition of the syncytium was stable. Besides, the syncytial wall pectin methyl-esterification status was shown to fluctuate along with the syncytium development in addition to coping with induced PEG-simulated drought stress. Further analysis was carried out on selected pectic homogalacturonan related mutants, and the fluorescence-based quantifications revealed the complexity of the forming and regulating pectin methyl esterification. Transgenic wheat lines with a root-cap-specific promoter were made via biolistics, in the hope of using this system to further investigate the syncytia formed in wheat, which were shown to be different from the other syncytia analysed.

Genetic characterization of resistance to stripe rust, leaf rust, Karnal bunt and cereal cyst nematode in a multiple disease resistant wheat stock W8627

Abstract: Genetic analysis of multiple disease resistance was carried out in segregating populations of bread wheat line W8627 and PBW343 against stripe rust (Puccinia striiformis), leaf rust (Puccinia triticina), Karnal bunt (Tilletia indica) isolates and cereal cyst nematode (Heterodera avenae). Seedling response of W 8627, PBW 343 and F1 against 78S84 race of Puccinia striiformis, 77-5 race of P. triticina reflected that the wheat line W8627 possessed seedling resistance genes against both the races. Based on the segregation pattern of F2 generation and F3 families, two complementary recessive genes for resistance to 78S84 race of Puccinia striiformis and one recessive gene each for resistance to 77-5 race P. triticina, mixture of Tilletia indica isolates and Ha 41 biotype of H. avenae were identified. Co-segregation studies revealed no linkage between concerned resistance genes.

Duplex PCR (polymerase chain reaction) detection method of heterodera avenae and heterodera filipjevi and application

Abstract: The invention discloses primer composition for duplex PCR (polymerase chain reaction) detection of heterodera avenae and heterodera filipjevi and an application of the primer composition The detection primer comprises HaF8:SEQ ID NO3, HfF9:SEQ ID NO4 and HafF8:SEQ ID NO5 A duplex PCR technology is used, the heterodera arenaria and the heterodera filipjevi are detected synchronously through a single reaction, and the detection cost for two pathogens and the workload are reduced A duplex PCR detection system which is high in specificity and sensitivity, time-saving, labor-saving and easy to operate is established, and the primer composition can be applied to rapid detection and/or identification of the heterodera avenae and the heterodera filipjevi

Estimation of genetic relationship of wheat germplasm against cereal cyst nematodes using RAPD technique

Abstract: Investigations were conducted at molecular level, to estimate genetic diversity among wheat germplasm (20 cultivars/lines) in relation to their response against cereal cyst nematodes Heterodera avenae, through Random Amplified Polymorphic DNA (RAPD) technique. A total of 589 bands were generated using 14 primers with an average of 28.8 bands/genotype. Maximum percentage of polymorphic loci was 92.86% for genotype TJ-83. Inferences have been made regarding bioassay and molecular characterization that the most diverse and resistant genotype against CCN was Moomal-2002 as compared to the rest of the genotypes studied and the most effective loci to screen diversity was OPA-09.

Primer combination with heterodera avenae EST-SSR (expressed sequence-simple sequence repeat) molecular markers and application of primer combination

Abstract: The invention discloses a primer combination with heterodera avenae EST-SSR (expressed sequence-simple sequence repeat) molecular markers and application of the primer combination. Primer sequences of the primer combination with the heterodera avenae EST-SSR molecular markers are shown as SEQ ID NO:1-16. EST data information is analyzed by the aid of MISA software according to transcriptome sequence information of heterodera avenae, large quantities of SSR loci are searched, and EST-SSR primers are designed according to SSR flanking sequences. The primer combination and the application have the advantages that the 8 EST-SST molecular markers which are high in polymorphism are screened by means of STR (short tandem repeat) typing detection after PCR (polymerase chain reaction) amplification is carried out, and the genetic diversity of 17 geographic populations of heterodera avenae can be effectively analyzed; the primer combination can be applied to research on population genetic structures, the genetic variation level and the like of the heterodera avenae in China.